Fuel injection system for internal combustion engines



FL A. MORRIS April 2, 1968 FUEL INJECTION SYSTEM FOR INTERNAL COMBUSTION ENGINES 3 Sheets-Sheet 1 Filed Dec. 28, 1965 INVENTOR. Ffwnk 14. Morrbs BY 9% W ATTORNEYS April 1968 F. A. MORRIS 3,375,811

FUEL INJECTION SYSTEM FOR INTERNAL COMBUSTION ENGINES Filed Dec. 28, 1965 3 Sheets-Sheet f3 INVENTOR.

BY 3 9 6W W 9 ATTORNEYS April 2, 1968 F. A. MORRIS 3,375,311

FUEL INJECTION SYSTEM FOR INTERNAL COMBUSTION ENGINES Filed Dec. 28, 1965 3 Sheets-Sheet 5 INVENTOR.

Fran]; 14. Morris 9mm, W6? W ATTORNEYS United States Patent Ofiice 3,375,811 FUEL INJECTION SYSTEM FOR INTERNAL COMBUSTION ENGINES Frank A. Morris, Box 534, Malvern, Ohio 44644 Filed Dec. 28, 1965, Ser. No. 516,962 11 Claims. (Cl. 123-139) ABSTRACT OF THE DISCLOSURE A fuel injection system for internal combustion engines including a fuel supply tank, a common fuel transfer and metering distributor having a central barrel, plural outlets opening into the barrel, an engine-driven rotary valve in the barrel, governor means to locate the rotary valve axially in response to engine speed, a second governor means to determine the range of axial movement of the valve permitted in response to engine speed, a unit injector for The invention relates to fuel injection systems for internal combustion engines, and more particularly to such a system that provides common metering for all cylinders so as to eliminate calibration adjustment for balance between cylinders.

A primary object of the invention is to provide a fuel injection system for an internal combustion engine, including a distributor with fuel pump communicating with fuel supply, and a plurality of fuel outlets each communicating with an injector for each cylinder of the engine.

Another object of the invention is to provide such a fuel injection system in which there is remote common by-pass metering in the distributor and there is communication from the supply pump to a pumping plunger to the fuel tank in each injector.

Still another object of the invention is to provide a pumping plunger for each cylinder, and to so isolate metering and pumping functions that injector failure, as may be due to plugged orifices or seized plungers, will not result in complete pump failure and resultant engine failure.

A further object of the invention is to provide a constant-stroke, constant-displacement pumping plunger at each cylinder, together in combination with a common bypass-metering distributor so that the timing of the injection portion of the pumping stroke may be varied according to the requirements of the engine.

A still further object of the invention is to provide a land upon the distributor rotor so that injection timing with respect to engine load is a function of the rake of the leading edge of the land, and this rake angle may be determined independently for the best operation of the engine, or for any particular application of the engine.

It is also an object of the invention that the profile of the trailing edge of the land maybe independently determined for best operation of the governor, as governor stability usually requires greater fiyweight travel at lighter loads and this condition is provided by the concave profile of the trailing edge.

Another object of the invention is to provide for an automatic and variable timing advance operated by the speed of the engine.

Still another object of the invention is to provide independent speed-responsive and load-responsive timing advance means, so that the degree of timing advance for any ing injection.

3,3 75,8 1 l Patented Apr. 2 1968 particular combination of engine speed and load is determined by the simultaneous action of both.

A further object of the invention is to provide a distributor head separated from pumping functions, so that odd or even numbers of cylinders may be served by the distributor, and that this distributor head may be drilled to accommodate regular or irregular firing intervals between cylinders, so that the configuration of the engine may be more readily chosen for balance, for manufacturing utility, or -for dimensional compatability with the proposed application. i

A still further object of the invention is to control fuel metering for all cylinders by one unit, so as to minimize governor linkage complexities and inertia values.

It is also an object of the invention to combine the governor with the distributor head so as to isolate the governor from the torsional acceleration produced by the pumping plungers. I

Another object of the invention is in combining the fuel metering means upon the governor sleeve, ,so that zero lash is maintained between the speed-sensing .and .fuel metering means, throughout the wear-life of the unit.

Still another object of the invention is: to provide for assurance of complete volumetric charging of the injector plunger by maintaining continuous communication be tween the injector plunger and the supply fuel except dur- A further object of the invention is the driving of the pumping plunger by a camshaft so that the rate of plunger travel may be independently determined by the selection of the cam profile, for the best operation of the engine.

A still further object of the invention is the elimination of after-injections resulting from the pressure wave rebound in the fuel line, since the pressure within the fuel line at the end of injection is vented to the entire mass of fuel at supply pressure.

It is also an object of the invention to provide a vent at each injector for the escape of air, for easy initial and continuous priming of the injector.

Another object of the invention is the provision of such a vent to provide circulation therethrough of the fuel, so as to minimize expansion of the fuel due to heating, and thus to maintain the heat value per unit volume of fuel injected, and so to maintain the accuracy of the maximum fuel limit throughout the range of operating temperatures.

A further object of the invention is to provide a vent of this character to provide the shortest leak-path for the high pressure leakage from the pumping plunger, for return to the fuel tank.

Finally, it is an object of the invention to provide for automatic regulation of maximum fuel delivery, so as to provide additional fuel for starting, a nominal maximum for speeds up to the torque peak of the engine, and forfuel reduction beyond this speed, so that the fuel quantity may parallel the decreasing weight of air within the cylinder.

The above and other objects, apparent from the'drawingsand following description, may be attained, the above described difiiculties overcome and the advantages and results obtained, by the apparatus, construction, arrangements. and combinations, subcornbinations and parts which comprise the present invention, a preferred embodiment of which, illustrative of the best mode in which applicant has contemplated applying the principle, being set forth in detail in the following descriptionand illustrated in the accompanying drawings, in which;

FIG. 1 is a vertical sectional viewthrough the distributor and associated parts of a fuel injection system embodying the invention, showing the parts thereof in the positions they assume when the engine is at rest;

FIG. 2 is a vertical sectional view of the same with the parts in the positions they assume with the engine at maximum operating speed;

FIG. 3 is a horizontal section through the fuel pump taken as on the line 33, FIG. 1',

FIG. 4 is a transverse section taken as on the line 4-4, FIG. 1;

FIG. 5 is a transeverse section taken on the line 5-5, FIG. 2;

FIG. 6 is a transverse section through the distributor head taken as on the line 66, FIG. 2;

FIG. 7 is a transverse section showing the advance flyweights when the engine is at rest, taken on the line 7-7, FIG. 1;

FIG. 8 is a similar view, taken on the line 88, FIG. 2 showing the advance fiyweights in the position they assume during maximum speed operation of the engine;

FIG. 9 is a longitudinal sectional view through one of the injectors showing the cam shaft for operating the same;

FIG. 10 is a fragmentary, vertical sectional view taken as on the line 10-10, FIG. 4; and

FIG. 11 is a schematic view of the improved fuel injection system, on a smaller scale.

' For the purpose of best illustrating the invention, the

common bypass-metering distributor shown is that for an irregular firing V-12 engine, either two or four-stroke cycle operating at a constantspeed which is above the torque peak of the engine.

Referring-now particularly to the construction illustrated in the drawings, in which similar numerals refer to similar parts throughout, the shaft 1 is adapted to be driven in the direction of the arrows shown on the drawings, at engine cam shaft 1:: speed.

The shaft 1 is journalled through the cover 2 of the fuel supply pump and the pump housing 3. Pump gear 4 is fixed to shaft 1 as by key 5. An idler gear 6 is a running fit upon stub shaft 7 which is pressed into pump cover 2.

'Pump cover 2 is attached to pump housing 3 as by screws 8.

A cylindrical pilot extension 10 is provided upon pump cover 2 so that the unit may replace the usual spark ignition distributor. assembly where the same basic engine is to be adaptable for either spark-ignition or compressionignition operation. Flange 11 upon the pump cover 2 provides seating for a hold-down clamp (not shown).

Pump housing 3 is provided with a fuel inlet opening 12 connected to the fuel supply tank T, as by the tubing 9, and with the drilled outlet passage 13. Horizontal by-pass passage 14 is drilled in pump housing 3 to communicate with the outlet passage 13, and is enlarged at 15 to enclose relief plunger 16, plunger spring 17 and threaded plug 18.

Plunger 16 normally closes aperture 19, which is drilled in the same plane as outlet passage 13, and communicates at its lower end with fuel inlet opening 12. Horizontal passage 20 intersects outlet passage 13 and is located above by-pass passage 14 as 'best shown in FIGS. 1 and 2.

Shut-off plunger 21 is slidably fitted into drilled horizontal passage 20, in which is also located plunger return spring 22. Shut-off operating lever 23 is pivotally attached to pump bodyhousing 3 by pivot pin 24.

A weight spider 25 is attached to shaft 1, as by key 26 and nut 27 upon reduced threaded portion 1b of shaft 1. A pair of advance fiyweights 28 are fitted free to swing on pivot pins 30 which are pressed into weight spider 25. Spring pins 32 are pressed into fiyweights 28 and extend through slots 34 in weight spider 25.

Advance springs 36 are attached at opopsite ends to pivot pins 30 and spring pins 32 so as to normally hold flyweights 28 in the closed position. Fulcrum pins 38 are pressed into advance flyweights 28 and engage slots 40 in advance sleeve 42 which is slidably fitted on shaft 1 and has holes 43 drilled therein into which sleeve studs 45 are slidably fitted.

The lower ends of sleeve studs 45 are pressed into rotor 47 and the upper ends thereof are attached to lower spring seat 48 as by screws 49. Together, the sleeve studs 45, rotor 47, lower spring seat 48 and screws 49 comprise the rigid weight sleeve assembly. Slots 51 in the weight spider 25, through which the sleeve studs 45 are located, provide clearance for rotatably adjusting the weight sleeve assembly.

The lower ends of fuel limiting pins 53 (FIGS. 1, 2, 7 and'8) are pressed into the advance flyweights 28, the spherical upper ends thereof being held in contact with the contoured undersurface of advance sleeve 42, as will be later described, by the action of compression spring 55 which is fitted between, and acts to separate, advance sleeve 42 and lower spring seat 48.

Rotor 47 is a mated fit into the central bore 52 of distributor head 56 (FIGS. 1, 2 and 6), which is drilled for intersecting inlet passages 57 and 58 (FIG. 10), the latter of which communicates with outlet passage 13 in pump housing body 3.

Referring particularly to FIG. 6, radially disposed outlet passages 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69 and 70 are drilled in the distributor head 56, in a horizontal plane and angular spacing according to the firing intervals of the engine. Distributor head 56 is attached to pump body 3 as by screws 71 (FIGS. 1 and 2). Each outlet passage 59 through 70, in the distributor head, is connected to a fuel injection tubing 73, by a nut 74 and ferrule 75.

Arm extensions 76, of weight spider 25, support weight pins 78 (FIGS. 1 and 2) about which regulating flyweights 80 are pivoted. Governor spring 82 extends downward against lower spring seat 48 and upward against thrust bearing 83, the downward thrust of governor spring 82 being accepted by lower thrust bearing 84.

A generally cylindrical upper cover 85 is attached to the distributor head 56 as by screws 86. Shaft bushing 88 is pressed into upper extension 87 of cover 85, and upper end of shaft 1 is journalled therein.

Referring now more particularly to FIG. 9, the other end of each fuel injection tubing 73 is connected through nut 89 and ferrule 90 to the injector body 91 for the corresponding cylinder and in communication with the injector inlet passage 92 thereof.

Bushing 93, in upper end of injector body 91, is a mating fit with injector plunger 94. Bushing 93 is held in place in injector body 91 by lower spring seat 95 which is threaded onto the upper end of injector body 91.

Plunger return spring 96 is contained between lower spring seat 95 and upper spring seat 97 which is notched onto plunger 94 as shown. Vent 98 is radially drilled through bushing 93 to communicate with peripheral collector groove 99 on the exterior of bushing 93.

Collector groove 99 in turn communicates with overflow passage 100 in the injector body, and through overflow line 101, attached by line nut 102, for return to the top of the fuel tank T.

Discharge passage 103 connects the plunger cavity .with check ball 104 and communicates, intermediate its ends, with inlet passage 92. Check ball spring 105 fits into enlarged bore 106 of spray tip 107. Check ball spring 105 has a longer free limit than the bore 106 so that check ball 104 will not open with supply pump pressure. Enlarged bore 106 communicates with passage 108 and through the same with spray orifices 109. Retainer nut 110 threads onto injector body 91 to hold spray tip 107 in place.

Injector cam lobe 111 is formed upon engine valveoperating cam shaft 1a, and injection rocker arms 113 and 113 pivot on fixed rocker arm shaft 114.

Referring again to FIGS. 1, 2 and 6, a peripheral groove 115 is formed in the rotor 47, registering with the outlet passages 59 to 70 inclusive in the distributor head 56. A land 116 is formed upon the rotor 47 in said. groove 115 and extends from the top of said groove to a point spaced from the bottom thereof, as shown at 117 in FIG. 1. The leading edge 118 of the land 116 is shown as inclined downwardly and forwardly to the axis of shaft 1, and the trailing edge 119 is shown as concave, for reasons to be later explained.

Having described the illustrated embodiment of the novel fuel injection system, the operation thereof is as follows. The shaft 1, being driven by the engine, in the direction of the arrows and at engine cam shaft 1a speed, drives pump gears 4 and 6 in the directions shown in FIG. 3, pumping fuel fro-m the fuel supply tank T, through tubing 9 and inlet 12.

The fuel is discharged from the pump upwardly through the outlet passage 13, and through connecting passages 58 and 57 (FIG. 10) in the distributor head 56, to the groove 115 in rotor 47, thence outward through the radial outlet passages 59 to 70 inclusive, each being connected to an identical unit injector, as shown in FIG. 9 and as above described.

The fuel flowing outward through fuel line 73 to the unit injector shown in FIG. 9, enters the inlet passage 92 thereof filling the connecting passage 103 and then upward to fill the space below the plunger 94, then outward through the restricted vent 98 to the overflow passage 100 and the overflow line 101 for return to the top of the fuel supply tank T.

Each outlet passage 59 through 70 of the distributor head is in continuous communication with the supply fuel except when closed by the land 116 on the rotor 47. Flow of fuel through the vent 98 of each injector unit continues as long as the corresponding rocker arm 113 rests on the base circle 123 of the cam, when the corresponding injector plunger 94 is raised to the upper limit of travel by return spring 96.

The injection cam lobe 111, formed upon engine valveoperating cam shaft 1a, is rotated in the direction of the arrow in FIG. 9, to depress plunger 94 through the action of rocker arm 113.

The injector plunger 94, beginning downward travel, first closes off vent 98, then begins to displace fuel down.- ward through passage 103, through inlet passage 92, through fuel line 73, through outlet passage 59 to groove 115 of the rotor 47.

This backward flow continues during the downward travel of plunger 94, until the land 116 of rotor 47, which is rotating in the direction of and along with shaft 1, closes off passage 59. Further downward movement of plunger 94 will cause a pressure rise unseating check ball 104, and the fuel will be discharged through passage 108 and spray orifices 109 into the corresponding cylinder combustion space.

Injection continues until the trailing edge 119 of land 116 uncovers passage 59, after which backward displacement of the fuel into rotor groove 115, as above described, continues until plunger 94 has reached the bottom of its stroke. This flow reverses as the plunger begins to rise and the above-described fill and vent cycle begins.

The pump gears 4 and 6 have a greater output than is required to charge the plunger and to maintain the restricted flow through the injector overflow lines. Consequently, as the output pressure rises (see FIG. 4) relief plunger 16 is unseated and partially uncovers aperture 19 which allows fuel to be bypassed to the inlet side of the pump. The supply pump pressure is then regulated by the tension of plunger spring 17.

The weight spider 25, attached to and rotating with shaft 1, carries advance flyweights 28 on fixed pivot pins 30. Advance sleeve 42 is then driven, through slots 40, by fulcrum pins 38 which are fixed into flyweights 28. The weight sleeve assembly (members 45 through 49) is then driven by advance sleeve 42, through holes 43 into which sleeve studs 45 are slidably fitted.

In FIGS. 1 and 7 are shown the positions of the flyweights 28 and the sleeve studs 45, relative to the keyway axis of shaft 1, when the engine is at rest. When the engine has reached the maximum operating speed, advance flyweights 28 have become fully extended overcoming the tension of advance springs 36.

Flyweights 28, moving outward toward this limit, act upon advance sleeve 42, through the action of fulcrum pins 38, to rotate advance sleeve 42 and the weight sleeve assembly, through slidably fitted weight sleeve studs 45, to the position indicated in FIGS. 2 and 8, rotatably adjusting the weight sleeve assembly in the direction of rotation of shaft 1.

While the injector plunger will still travel in a fixed relation to the rotation of engine cam shaft 1a, the land 116 of rotor 47 will close off passage 59, in distributor head 56, earlier in the downward travel of injector plunger 94, to advance the timing of the injection phase of the plunger travel. I

Speed regulating flyweights 80, being rotated along with weight spider 25, pivot outward on weight pins 78 to bear upward upon the underside of the lower spring seat 48 and against the tension of governor spring 82. When the accelerating engine has exceeded the speed determined by the tension of governor spring 82, flyweight inertia overcomes spring 82 and raises the weight sleeve assembly (members 45 through 49) upward to where that portion of groove which lies below the land 116 is in register with outlet passages 59 through 70, and injection ceases.

As the engine speed then begins to slow down, spring 82 overcomes the reduced flyweight inertia to lower the Weight sleeve assembly (members 45, 4'7, 48 and 49) to the point where the width of that portion of land 116 which crosses outlet passages 59 through 70 represents a fuel injection quantity adequate to sustain the engine speed, provided the load is within the capacity of the engine.

When the governor is thus regulating the speed of the engine, lower spring seat 48 has moved upward and away from advance sleeve 42. Spring 55, acting to separate lower spring seat 48 and advance sleeve 42, holds ad vanee sleeve 42 downward upon fuel limit pins 53 and prevent advance sleeve 42 from riding upward and out of engagement with fulcrum pins 38.

FIGS. 1 and 7, which show the engine at rest, illustrate the position of fuel limit pins 53 at this time. In FIG. 1 the limit pins 53 have reached their inner limit of travel on the inner plane undersurface 120 of advance sleeve 42, permitting governor spring 82 to adjust the weight sleeve assembly (members 45, 47, 48 and 49) downward to where the greatest width of land 116 will cross the outlet passages 59 through 70 in the distributor head 56. The fuel quantity injected, as represented by this greater land width, is more than the engine can burn completely and economically, but this condition is required to facilitate starting in some engines.

After starting, as the engine accelerates, advance flyweights 28 move outward, carrying fuel limit pins 53 outward along the contoured undersurface of advance sleeve 42, to bear against and urge advance: sleeve 42 upward, and then to move outward to an outer plane surface 121, which represents the nominal maximum fuel delivery up to the torque peak of the engine.

As the engine is operating at a speed above the torque peak, further increase in speed above the torque peak causes the pins 53 to move further outward to the curved torque reduction area 122, where advance sleeve 42 is further adjusted upward until pins 53 have reached their outer limit of travel, further limiting the maximum fuel quantity by further limiting the downward travel of the weight sleeve assembly. This action prevents an excess fuel-to-air ratio because of the lessened volumetric efficiency at thisspeed.

FIG. 2 represents the positions of the parts of the distributor portion of the device with the engine in a stalling condition. As the overloaded engine falls off in speed, pins 53 will move inward along the torque reduction area 122, permitting downward adjustment of advance sleeve 42 and the weight sleeve assembly to increase the fuel injection delivery. If the load is within the torque capacity of the engine, the speed will not decrease further, and normal speed will be resumed if the additional load is removed.

As above pointed out, the leading edge 118 of land 1116 is shown at an angle to the axis of shaft 1. In the operation of the engine, when the load is decreased, the compensating upward adjustment of the weight sleeve assembly will cause injection to begin earlier. This light load advance characteristic may be varied to the degree required by the engine, or the leading edge 116 may be aligned with the longitudinal axis of shaft 1, in which case the beginning of injection would be constant with respect to engine load. The angle of the leading edge of the land might also be inclined in the other direction, that is downwardly and inwardly, to give a light load retard characteristic, if so required for the best operation of the engine.

As above stated, the trailing edge 119 of land 116 is shown concave, which condition requires greater flyweight travel to effect a change in fuel delivery at the lighter loads, where required to assure the governor stability, as to upset the latent oscillatory capability of linear-rate governor spring opposing a linear-rate delivery characteristic land, where both sides are straight.

FIG. shows the engine shut-down mechanism. When lever 23 is moved in the direction of the arrow, plunger 21 is moved against the tension of plunger return spring 22 to completely cover pump outlet passage 13.

All of the output of the gear pump is then recirculated through by-pass hole 14 (FIGS. 1, 2 and 4), past relief plunger 16 and through aperture 19 back to the pump inlet side. The gear thus retains its prime during shut-down. The injector plungers 94 draw air back through vents 98 from overflow lines 101 to become airbound. Brief cranking during start will reprime the injectors.

From the above it will be obvious that the improved fuel injection system provides common metering for all cylinders so as to eliminate calibration adjustment for balance between cylinders and that it provides a pumping plunger for each cylinder and thus isolates metering and pumping functions.

It is also obvious that the pumping plunger for each cylinder is a constant-stroke, constant-displacement plunger in combination with a common bypass metering distributor.

It will also be seen that the fuel injection system includes a distributor head with central bore in which a rotor is axially movable, there being radial outlet passages in the distributor head communicating with the central bore and a peripheral groove in the rotor com- A municating with the outlet passages, and a land upon the rotor within the peripheral recess; that the leading edge of the land may be inclined and the trailing edge thereof may be concave.

It will also be obvious that the various other objects of the invention are accomplished by the construction and operation of the fuel injection system as above described.

In the foregoing description certain terms have been used for brevity, clearness and understanding, but no unnecessary limitations are to be implied therefrom beyond the requirements of the prior art, because such words are used for descriptive purposes herein and are intended to be broadly construed.

Moreover, the embodiments of the improved construction illustrated and described herein are by way of example, and the scope of the present invention is not limited to the exact details of construction.

Having now described the invention or discovery, the construction, the operation, and use of preferred embodiments thereof, and the advantageous new and useful results obtained thereby; the new and useful construction, and reasonable mechanical equivalents thereof obvious to those skilled in the art, are set forth in the appended claims.

I claim:

1. In a fuel injection system for an internal combustion engine having a camshaft, said fuel injection system including a fuel tank, a combined unit including a fuel pump, a fuel metering device, and a distributor, a plurailty of pump injectors one for each cylinder of the engine driven by said camshaft, a fuel circuit connecting said tank, said pump and said device in series, a shaft in said unit connected to drive said pump and adapted to be driven by said engine at camshaft speed, a distributor head on said unit, a bore in said unit axially aligned with said shaft, a plurality of circumferentially spaced outlets on said head each connected to one of said pump injectors and opening into said bore, and a rotary valve in said bore driven by said shaft and located therein and provided with means thereon to sequentially open and close said outlets and axially moveable in said bore to vary the angular duration of Opening of said outlets the improvement comprising speed responsive timing advance means including a weight spider attached to said shaft, spring biased advance fiyweights pivotally mounted upon the weight spider to locate the rotary valve rotatably upon said shaft in response to engine speed, and a speed regulating governor including a second pair of spring biased governor flyweights pivotally mounted upon the weight spider for locating the rotary valve axially in response to engine speed.

2. A fuel injection system as defined in claim 1, there being a peripheral groove in said rotary valve communicating with said outlets in the distributor and with the discharge side of the fuel pump, and a tapered land in said peripheral groove.

3. A fuel injection system as defined in claim 2, in which the leading edge of said land is inclined relative to the longitudinal axis of said rotary valve.

4. A fuel injection system as defined in claim 2, in which the trailing edge of the land is concave.

5. A fuel injection system as defined in claim 2, in which the leading edge of the land is inclined downwardly and forwardly.

6. A fuel injection system as defined in claim 5, in which the trailing edge of the land is concave.

7. A fuel injection system as defined in claim 1, in which the rotary valve forms part of a sleeve assembly longitudinally movable upon said shaft.

8. A fuel injection system as defined in claim 7, in which said sleeve assembly is movable longitudinally upon the shaft by said governor means rotatable with the shaft.

9. A fuel injection system as defined in claim 1, in which the pumping plunger in each unit injector is a constantstroke constant-displacement plunger.

10. A fuel injection system as defined in claim 8, in which the sleeve assembly includes studs located through slots in the weight spider for rotatably adjusting the sleeve assembly.

11. A fuel injection system as defined in claim 10, including, an advance sleeve rotatably and slidably mounted upon the shaft, said studs being slidably located through apertures in said advance sleeve, the underside of the advance sleeve being an inner flat plane, and outer lower flat plane, a peripheral curved plane, fuel limiting pins on the flyweights, and spring means holding the ends of said pins in contact with the under surface of the advance sleeve.

References Cited UNITED STATES PATENTS 2,300,313 10/1942 Pool 1O3173 2,357,563 9/1944 Truxell 103173 2,408,298 9/1946 Cummins 123139 2,417,137 3/1947 Smith 103-173 X 3,185,140 5/1965 Cummins 123-139 3,319,568 5/1967 Repko et al. 123l40 X LAURENCE M. GOODRIDGE, Primary Examiner. 

